Crystal Radios were very simple. A crystal (hunk of galena -- lead ore), a tiny wire to poke into it to find a hot spot, a coil, an antenna, a ground and an earphone.
The simplest crystal set looks like this and can be home built easily. (note-- all photos here are from the internet and not of my own radios, now gone, but look like them).
|Coil with slider to tune, sharp pointed wire to poke into galena crystal (bottom right), and earphone and antenna and ground make a crystal radio.|
Eventually we had the boxtops (everyone saved boxtops from any product as sooner or later they would be useful for some deal) and the dollar.
A few weeks later it came. We opened the box, read the instructions, clipped the antenna coil to the wire clothesline, poked the earphone in our ear and sure enough, WCCO radio playing faintly if we tuned it by moving the rod up and down.
I found a few of these for sale on the internet today, and they ranged from $60 - 100. So instead of buying one, I instead downloaded the photos. A memory is good enough as I probably couldn't hear the faint stations anymore.
We ended up opening our radio, connecting a separate ground wire (soldering it on) that improved the signals and selectivity. Eventually we took it apart and used the diode (a modern replacement for the galena crystal) and loopstick in making our own radio.
|The original packaging from an Internet sales offer|
|The loopstick coil had a metal core that slid up and down to tune the radio.|
|Rocket Crystal Radios were made with the exact same insides, but more glamorous on the outside.|